Collated screw strip with support surface

ABSTRACT

A driver for fasteners, and particularly, a power screwdriver is described which is adapted to drive screws having different diameters. The power screwdriver has a removable guide tube and complementary drive shaft. The guide tube is sized to the diameter of one size of screw. The complementary removable drive shaft is sized to be guided in the guide shaft, reciprocally movable therein to engage and guide a screw located in the guide tube. By removal of one pair of guide tube and complementary drive shaft and replacement with another pair of guide tube and complementary drive shaft adapted for use with screws having a different head diameter, the driver is adapted for driving screws of different head diameters.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.08/545,399, now U.S. Pat. No. 5,699,704, which is a continuation-in-partof U.S. patent application Ser. No. 08/233,909, abandoned, filed Apr.28, 1994; Ser. No. 08/198,129, filed Feb. 17, 1994, now U.S. Pat. No.5,469,767 and Ser. No. 08/018,897, filed Feb. 17, 1993, now U.S. Pat.No. 5,337,635.

SCOPE OF THE INVENTION

This invention relates generally to a screwdriver for driving collatedscrews which are joined together in a strip, and a novel collated screwstrip adapted to facilitate alignment of screws in the screwdriver.

BACKGROUND OF THE INVENTION

Collated screws are known in which the screws are connected to eachother by a retaining strip of plastic material. Such strips are taught,for example, by U.S. Pat. No. 4,167,229 issued Sep. 11, 1979 and relatedCanadian Patents 1,040,600 and 1,054,982 the disclosures of which areincorporated herein by reference. Screws carried by such strips areadapted to be successively incrementally advanced to a position inalignment with and to be engaged by a bit of a reciprocating, rotatingpower screwdriver and screwed into a workpiece. In the course of the bitengaging the screw and driving it into a workpiece, the screw becomesdetached from the plastic strip leaving the strip as a continuouslength.

In the use of such collated strips in screwdrivers, the strip serves afunction of assisting in guiding the screw into a workpiece and, toaccomplish this, the strip is retained against movement towards theworkpiece. In the strip, each screw to be driven has its threaded shaftthreadably engaged in a threaded sleeve of the strip such that on thescrewdriver engaging and rotating each successive screw, the screw turnswithin the sleeve which acts to guide the screw as it moves forwardlyinto threaded engagement into the workpiece. Preferably, only after thetip of the screw becomes engaged in the workpiece, does the head of thescrew come into contact with the sleeves. Further forward movement ofthe screw into the workpiece then draws the head downwardly to engagethe sleeve and to rupture the sleeve by reason of the forward movementof the head with the strip retained against movement towards theworkpiece. The sleeve preferably is configured to have fragible strapswhich break on the head passing through the sleeve such that the stripremains intact as a continuous length. Since the strip is a continuouslength, on advancing the strip with each successive screw to be driven,it necessarily results that portions of the strip from which each screwhas been driven are also advanced to exit from the power screwdriver.

Known power screwdrivers for driving such collated strips include U.S.Pat. No. 4,146,871 to Mueller et al, issued Mar. 27, 1976, and U.S. Pat.No. 5,186,085 to Monacelli, issued Feb. 16, 1993, the disclosures ofwhich are incorporated herein by reference. Such known powerscrewdrivers include a rotatable and reciprocally moving screwdrivershaft which is turned in rotation by an electric motor. A screw drivingbit forms a forward most portion of the shaft for engaging the head ofeach successive screw as each screw is moved into a driving position,axially aligned under the screwdriver shaft.

An important aspect of such power screwdriver is the manner and accuracywith which each successively advanced screw is positioned so as to beproperly aligned axially under the screwdriver shaft for successfulinitial and continued engagement between the bit and the screwdriverhead in driving a screw fully down into a workpiece. In the devices ofMueller et al and Monacelli, the strip is effectively held in position,notably, by reason of the device grabbing and fixing the position of thescrew beside the screw to be driven. These devices also teach locationof a screw to be driven in part by the head of the screw to be drivenengaging the surface in a guide channel in which the screwdriver bit isreciprocal. In each of Mueller et al and Monacelli, a specific footplateis provided to grasp and fix the position of the screw beside the screwto be driven. The footplate engages a workpiece and is spring biasedtowards the workpiece. On the device being brought into engagement withthe workpiece, the footplate retracts towards the device. The footplatehas a conical recess which engages the tip of the screw next to thescrew to be driven and applies a force to that screw pushing itrearwardly so that its head bears on a locating plate in the screw feedmechanism. By reason of this next screw being firmly clamped between thefootplate and locating plate, the strip is effectively locked intoposition and thereby positions the screw which is to be driven. Suchfootplates, however, have the disadvantage of being separate movableparts which must move forwardly to permit successive screws to beadvanced and then rearwardly to clamp the next screw.

Another disadvantage of prior art devices in which the device grabs thescrew beside the screw to be driven is that such systems do not permitthe very last screw in any strip to be driven without possibledifficulties. The last screw therefore frequently has to be discardedand/or may result in jamming. This is a particular disadvantage wherescrews are collated into strips which do not have a large number ofscrews. For example, in a simple strip of twenty-four screws, to discardevery twenty-fourth screw is a substantial disadvantage.

Another disadvantage of prior art devices appreciated by the applicantis that screw advance mechanisms such as those used in U.S. Pat. No.4,146,871 utilize pawls which on withdrawal of the pawl so as to be in aposition to advance the next successive screw of the screw strip tend tofrictionally engage and to some extent withdraw the entire screw stripwhen this is not required. Such "feed pawl drawback" is disadvantageousinsofar as it can withdraw a screw to be driven from axial alignmentwith the driver shaft.

SUMMARY OF THE INVENTION

Accordingly, to at least partially overcome the disadvantages ofpreviously known systems, the present invention provides an improvedscrewdriver assembly which supports the strip adjacent the screw to bedriven on the exit side of the screw.

An object of the present invention is to provide a screwdriver assemblyfor driving collated screws which has fewer parts and/or is inexpensiveto manufacture.

Another object is to provide an improved collated strip containingscrews which includes locating devices on the strip to assist inlocating screws to be driven.

Another object is to provide a collated screw strip and screwdrivertherefore which avoids difficulties with "feed pawl drawback".

The present invention provides in the context of collated screws orother fasteners collated together by a continuous strip which remainsintact after a screw has been driven from the strip, a screwdriverassembly which at least in part locates a screw to be driven byproviding a rearwardly directed strip supporting surface forward of thestrip to engage an exiting portion of the strip from which a screw hasbeen driven. The strip supporting surface may be complementarily shapedto the surface of the strip to be engaged. In a preferred embodiment,the strip supporting surface may have a projection or a notch to engagewith a respective complementary notch or projection in a forward mostsurface of the strip to more positively locate the strip.

The locating system comprising the strip supporting surface andcomplementary strip may be used alone or in conjunction with one or moreother locating features such as those in which the head of a screw isengaged within a guideway. The locating system of the strip supportingsurface and complementary strip is advantageous in permitting the lastscrew in a strip to be driven.

In one of its aspects, the present invention provides a screwdriverassembly to drive screws collated together in a strip spaced in parallelrelation from each other, the screwdriver comprising:

a cylindrical guideway to receive a screw coaxially therein,

a screw-and-strip entranceway opening generally radially into theguideway on a first side thereof,

a strip exit way opening generally radially out of the guideway on asecond side thereof opposite the entranceway,

the guideway entranceway and exit way juxta-positioned to permit screwscollated in a strip spaced in parallel relation from each other to besuccessively advanced through the entranceway radially into the guidewayto locate each successive screw coaxially within the guideway withportions of the strip from which screws have been driven extending fromthe guideway via the exit way,

elongate, rotatable driver shaft means having at a forward end bitmeans, the shaft means reciprocally movable axially in the guideway toengage the screw with the bit means and drive the screw axiallyforwardly from the guideway into a workpiece,

the exit way having an axially, rearwardly directed strip supportingsurface axially forward of the strip for engagement by the strip tosupport the strip against movement forwardly on the shaft means drivinga screw axially forwardly.

Preferably, the strip supporting surface includes a screwdriver assemblyas claimed in claim 1 wherein the strip supporting surface includessupport locating means to engage in registry with strip locating meanson the strip to locate the strip in a desired position to assist inmaintaining the screw coaxially disposed within the guideway.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects and advantages of the present invention will be apparentfrom the following description taken together with the drawings inwhich:

FIG. 1 is a pictorial front view of a power driver in accordance withU.S. Pat. No. 4,146,071 modified to incorporate a guide tube inaccordance with a first preferred embodiment of the present inventionand having a slide body in an extended position;

FIG. 2 is a cross-sectional top view of the power driver of FIG. 1 alongsection line II-II';

FIG. 3 is a schematic cross-sectional front view of the power driver ofFIG. 2 along section line III-III';

FIG. 4 is an exploded partially pictorial view of the front of the slidebody of the power screwdriver together with the guide tube as shown inFIGS. 1, 2 and 3;

FIG. 5 is a partial cross-sectional top view along section line V-V' inFIG. 4 with the guide tube inserted in the slide body;

FIGS. 6 and 7 are views similar to FIGS. 4 and 5 but with the guide tubeand slide body modified to have a configuration in accordance with asecond embodiment;

FIGS. 8 and 9 are views the same as FIGS. 6 and 7 respectively but withthe guide tube modified to have a configuration in accordance with athird embodiment;

FIG. 10 is a perspective view of a screw strip in accordance with afourth embodiment of the present invention having locating notches orslots;

FIG. 11 is a view similar to that of FIG. 4 showing the guide tube ofFIG. 4 modified for use with the notched screw strip of FIG. 8;

FIGS. 12 and 13 show the embodiment of FIG. 11 with the screw strip indifferent relative positions in a feed cycle;

FIG. 14 is a pictorial view of a guide tube in accordance with a fifthembodiment of the present invention adapted for use with the notchedscrew strip of FIG. 10;

FIG. 15 shows a perspective view of a screw strip in accordance with afifth embodiment of the present invention;

FIG. 16 is a front elevation view of one screw in the strip of FIG. 15;

FIG. 17 is a cross-sectional end elevation view of the strip in FIG. 16along line 17-17';

FIG. 18 is a cross-sectional end elevation view of the strip of FIG. 16along line 18-18'; and

FIG. 19 is a rear view of the strip of FIG. 16.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is made first to FIGS. 1, 2, and 3 which show in part anelectrically powered screwdriver 10 of the type disclosed in U.S. Pat.No. 4,146,071. The screwdriver 10 is used in driving screws 12 whichhave been collated and secured together in a parallel spacedrelationship by a retaining strip 14 preferably of plastic. Such strips14 are taught in U.S. Pat. No. 4,167,229.

The screwdriver 10 includes a chuck 18 which is rotated by an electricmotor of a power driver not otherwise shown. The chuck 18 engages an endof an elongate metal shaft 20 best seen in FIG. 3 consisting of agenerally cylindrical metal mandrel 22 having removably secured to alowermost end thereof, an axially aligned metal bit 24. The bit 24defines at a forward most end a screw driving tip 23, adapted forengaging a complementary shaped recess 13 formed in the head 16 of thescrew 12. In a manner described in greater detail hereafter, whilerotating, the mandrel 22 carrying the bit 24 is reciprocated withincylindrical guideway in a guide tube 26 to engage and drive successivescrews 12 into a workpiece 28. The guide tube 26 is secured in slidebody 52. The screwdriver 10 of the present invention in essence hasidentical elements and operates to drive screws in an identical mannerto that disclosed in U.S. Pat. No. 4,146,871.

In this regard, as best seen in FIGS. 1, 2 and 3, the screwdriver has ahousing 70 to which a power driver (not shown) is fixed by the powerdriver's chuck 18. Slide body 52 is coupled to housing 70 for slidingdisplacement parallel to a longitudinal axis through the shaft 20between an extended position as shown in FIG. 1 and a retracted positionshown in FIG. 3. Coil spring 66 biases the slide body 52 relative to thehousing 70 to the extended position. The slide body 52 includes a guidechannel for the screw strip 14 carrying the screw 12. The guide channelis defined under a removable cover plate 72 shown in FIG. 1 andremovable by thumb screw 74. The guide channel is best shown in theenlarged view of the front of the slide body in FIG. 4 with the coverplate 72 removed. In FIG. 4, a groove 76 receives the head of a screw 12with the top of a screw engaging surface 77. A screw feed advancemechanism is mounted in slide body 52 and activated by relative movementbetween the housing 70 and the slide body 52. In this regard, pawl arm78 shown in FIGS. 3 and 4 reciprocates back and forth to advancesuccessive screws. Pawl arm 78 is moved by a mechanical linkageincluding lever 68 moved by wheel 80 engaging ramped surface 82 of thehousing 70 shown in FIGS. 1 and 3 on the slide body 52 reciprocatingbetween extended and retracted positions.

FIGS. 4 and 5 show a guide tube 26 adapted to be removably secured in acylindrical bore 54 which extends through slide body 52, and in thisregard, each has a complementary shape. To locate the guide tube 26within the bore against axial rotation, one side of the guide tube has aflat external surface 79 to mate with a corresponding flat surface 81 inthe otherwise generally cylindrical bore 54. The exterior of the guidetube has a stepped configuration with a reduced diameter rear section 82and a larger diameter main portion 83 with a rearwardly directedshoulder 84 therebetween. The bore 54 is similarly shaped to axiallylocate the guide tube as best seen in FIG. 5 with a correspondingforwardly directed shoulder 85 in the bore 54. As seen in FIG. 4, a slot86 is cut into the guide tube into which slot the rearmost left handcorner of the cover plate 72 shown in FIG. 1 will fit such that thecover plate will retain the guide tube 26 secured in place.

The slide body 52 carries a foot plate 200 which is slidably mounted tothe slide body 52 for sliding in a direction parallel the longitudinalaxis of the shaft 20 between an extended position shown in FIG. 1 and aretracted position shown in FIG. 3. The foot plate 52 is biased to theextended portion by a spring (not shown) acting between the foot plateand the slide body. The foot plate 200 has a touchdown surface 202 toengage a workpiece, an opening 204 through which a screw 12 is to bedriven, and a conical locating recess 206 best seen in FIG. 3.

The present invention is focused on features of the guide tube 26 andits interaction with screw strip 14. A cylindrical bore or guideway 32extends axially through the center of the guide tube 26 with theguideway 32 delineated and bordered by a radial extending cylindricalsidewall 34, and open at its forward axial end 36 and its rearward axialend 38.

Portions of the side wall 34 are removed to provide, firstly, anentranceway generally indicated as 48 for the strip carrying eachsuccessive screw 12 to enter the guide tube 26 on an entry side of thetube and, secondly, an exitway generally indicated as 50 on the exitside of the guide tube 26 opposite the entry side for the strip 14' fromwhich the screws have been driven to exit guide tube 26.

The entranceway 48 is sized so as to permit the strip carrying a screwto enter the guideway 32 moving generally radially while beingmaintained parallel to the axis of the guide tube. The exitway 50, isprovided of a size to permit the spent plastic strip 14' from whichscrews 12 have been driven to exit from the guideway 32.

As best seen in FIG. 4, the exitway 50 is defined by forward surface 93,side surface 94 and rear surface 95.

The forward surface 93 is provided as seen in FIG. 4 by a portion 96 ofthe sidewall 34 forward of the exitway 50 being retained between flatsurface 79 and a parallel inner surface 97 extending upwardly from whereit is tangent to the inner sidewall 34.

The forward surface 93 is provided as an axially, rearwardly directedstrip supporting surface which is axially forward of the strip forengagement of the strip to support the strip against movement forwardlyon the shaft 20 driving a screw forwardly. As best seen in FIG. 5, theforward surface in effect provides a rearwardly directed shoulder toengage a forward surface 122 of the strip 14 and prevent its forwardmovement. With the forward surface 93 and the forward surface 122 of thestrip 14 having complementary shapes, as shown with both being flat andplanar in FIG. 5, their engagement assists in holding a screw axially inalignment with the bit 24.

Similar to forward surface 93, the rear surface 95 of the exitway 50 asshown in FIG. 5 is provided as an axially, forwardly directed stripsupporting surface which is axially rearward of the strip 14. The rearsurface 95 in effect provides a forwardly directed shoulder which canengage a rear surface 123 of the strip 14 to assist in maintaining thestrip 14 guided within the exitway 50.

The guide tube 26 is indicated as having a rearward portion 40 adjacentthe rearward axial end 38 and a forward portion 46 adjacent the forwardaxial end 36. In rearward portion 40 of the guide tube 26, the sidewall34 preferably extends 360°. As seen best in FIG. 4, the forward portion46 is shown as having a first engagement section 42 and a forward mostsection 44.

The forward position 46 has substantially throughout its length theentranceway 48, shown in the drawings as being on the right hand side ofthe guide tube 26. This entranceway or access opening 48 extends to theforward axial end 36 of the guide tube 26. The entranceway 48 is sizedto permit the strip 14 carrying a screw 12 to move radially inwardlyinto the guideway 32 from the right as seen in the Figures. As the screwpreferably has a screw head diameter marginally smaller than thediameter of the sidewall 34, it follows that where the head of the screwis to enter the guideway 32, the entranceway 48 must have acircumferential extent of at least about 180°. Where the shank of thescrew is to enter the guideway, the entranceway may have a lessercircumferential extent.

The first engagement section 42 of the forward portion 46 is a sectioninto which the head of a screw 12 is moved when the strip 14 and screw12 are advanced. In the first engagement section 42, the wall 34 of theguide tube 26 engages the radially outermost periphery of the head 16 ofthe screw 12, to axially locate the screw head 16 coaxially within theguideway 32 in axial alignment with the bit 24. In this regard, in theforward engagement section 42, the walls 34 extend about the screwssufficiently to co-axially locate the screw head. The first engagementsection 42 preferably extends about the screw head at least 120°, morepreferably, at least 150° and, most preferably, about 180°.

When the guide tube 26 is fully inserted and secured in the bore 54, theforward portion 46 extends beyond a front surface of the slide body 52 asufficient distance such that the screws 12 are aligned with entranceway48 and retaining strip 14 is aligned with exitway 50.

The shaft 20 is adapted for sliding insertion into the guide tube 26 viathe rearward axial end 38. The interior sidewall 34 in the rear portion40 of the guide tube journals the continuous cylindrical exteriorsurface of the cylindrical mandrel 22. Thus, as seen in FIG. 3 the guidetube 26 journals the mandrel 22 within the bore 54 with the mandrelspaced from the walls of the bore rearward of the guide tube.

With the guide tube 26 secured in the slide body 52, the mandrel 22 andbit 24 are axially aligned with the guide tube 26 by engagement with thesidewall 34 to maintain the shaft 20 substantially coaxially aligned inthe guide tube 26.

As best seen in FIG. 3, the screws 12 to be driven are collated to beheld parallel and spaced from each other by a plastic retaining strip14. In use of the strip 14 in the screwdriver 10, in order for eachsuccessive screw 12a to be engaged and driven into the workpiece 28,each screw 12a is first advanced into axial alignment with the mandrel22 and bit 24 by the pawl arm 78 of the screw feed mechanism. The screwfeed mechanism engages and advances the plastic strip 14 as the bit 24and mandrel 22 are moved in the return stroke away from the workpiece 28under the force of spring 66. The screws 12 are moved radially into theguideway 32 through the entranceway 48. The advanced screw 12a is heldin position in axial alignment with the shaft 20 and bit 24 with itsscrew head 16 abutting the sidewall 34 in the first engagement section42 of the guideway. As the screw 12a is moved into the cylindricalguideway 32, the leading portion of the strip 14' from which screws havepreviously been driven extends outwardly from the guideway 32 throughthe exitway 50 in the forward most section 44, permitting substantiallyunhindered advance of the screws 12 and strip 14.

The cylindrical guideway 32 has a diameter which is selected so that theportion of the sidewall 34 about the entranceway 48, engages andsupports an outermost circumferential surface of the screw head 16.

In operation, with the guide tube 26 inserted into slide body 54, a bit24 having the desired screw driving tip 23 is secured to the mandrel 22and the bit 24 and mandrel 22 are located in the guideway 32 aspreviously described. A number of screws 12 collated by plasticretaining strip 14 are inserted into the screwdriver 10. To drive screw12a into workpiece 28, the power driver is activated to rotate the shaft20. The mandrel 22 and bit 24, while they are rotated, are reciprocallymovable in the guideway 32 towards and away from the workpiece 28. In adriving stroke, manual pressure of the user pushes the housing 70towards the workpiece 28. With initial manual pressure the footplate 200engages the workpiece 28 and the footplate 200 is slid rearwardly fromthe extended portion of FIG. 1 to its retracted position of FIG. 3 sincethe spring biasing the footplate 200 forwardly is not as strong as thespring 66. In moving rearwardly, the conical locating recess 206receives the tip of the screw 12b next to the screw 12a to be driven.The footplate 200 urges the screw 12b into surface 77 thereby securelyand precisely locating screw 12b in a relation parallel the axis of thedrive shaft 20. With screw 12b being securely located, the plastic strip14 holding the screw 12a assists in locating screw 12a in alignment withdrive shaft 20.

Manual pressure of the user first telescopes the footplate 200 to theretracted portion where the footplate's rearward sliding is prevented byscrew 12b, thereafter manual pressure compresses spring 66 so as to moveslide body 52 relative the housing 70 into the housing 70 from anextended position to a retracted position. on release of this manualpressure, in a return stroke the compressed spring 66 moves the slidebody back to the extended position thereby returning the mandrel 22 andbit 24 by moving them back from the workpiece 28.

In a driving stroke as the shaft 20 is axially moved towards theworkpiece 28, the driving tip 23 engages the screw head 16 to turn thescrew 12a in rotation. As is known, the plastic strip 14 is formed torelease the screw 12a as it is turned in rotation by the bit 24.Preferably, on release of the screw 12a, the plastic strip 14 deflectsaway from the screw 12a outwardly through the exit opening 50 so as notto interfere with the screw 12a in its movement into the workpiece 28.After the screw 12a is driven into the workpiece 28, the mandrel 22 andbit 24 are axially moved away from the workpiece 28 under the force ofthe spring 66 and a successive screw 12 is moved via the screw feedadvance mechanism through the entranceway 48 into axial alignment withthe shaft 20.

Reference is made to FIGS. 6 and 7 which show as a second embodiment ofthe present invention, a modified guide tube 26 and slide body 52adapted for driving a screw strip 14 in which hexagonally-headed screws12 carry washers 208 between the strip 14 and the tips of the screws.Such a screw strip 14 carrying washer 208 may preferably be of the typedisclosed in U.S. Pat. No. 4,930,630 to Habermehl issued Jun. 5, 1990which is incorporated herein by reference.

Guide tube 26 in FIGS. 6 and 7 is identical to guide tube 26 in FIGS. 4and 5 with two exceptions.

Firstly, the guide tube 26 of FIGS. 6 and 7 is shown with the firstengagement portion 42 as having an internal sidewall 134 of a diametergreater than the interior diameter of sidewall 34 in the rear portion40. The interior diameter of the forward portion 46 is shown to belarger so as to permit fasteners to be driven which have a greater headdiameter than the diameter of the mandrel, or which require a socket 210as shown in FIG. 7 or a bit which is of a greater diameter than thediameter of the mandrel 22. In FIG. 7 the socket 210 is shown as havinga diameter marginally less than that of the internal sidewall 134 suchthat engagement between the sidewall 134 and the socket 210 assists incoaxially locating the screws 12 in the guide tube 26 once a screw maybe engaged by the socket 210. FIG. 7 shows the mandrel 22 carrying asocket 210 to engage the hexagonal heads of screws 12. The enlargeddiameter sidewall 134 extends rearwardly beyond the entranceway 48sufficiently to permit the socket 210 to be withdrawn rearwardly behindeach screw to be driven.

Secondly, the guide tube 26 of FIG. 6 and 7 is shown with a secondengagement portion 47 having a sidewall 234 with an internal diameterwhich is greater than the interior diameter of sidewalls 34 and 134. Thediameter of the sidewall 234 in the second engagement portion 47 ismarginally greater than that of the washers 208 such that engagementbetween the sidewall 234 and the washers 208 assists in coaxiallylocating the screws 12 in guide tube 26. Preferably as shown thesidewall 234 extends about the washer 208 about 180° to maximize theability of the sidewall 234 to locate the washer 208. As shown anentranceway 212 is provided radially into the second engagement portion47 from the right between entrance ramp surfaces 214 and 216 whichassist in guiding a washer 208 into the second engagement portion 47.The sidewall 234 need not extend 180° about the washer but preferablyextends there about at least 120°. The entranceway 212 must have acircumferential extent of at least about 180° where the washer 208 is toenter.

FIGS. 6 and 7 also show minor modifications of the footplate 200 so asto avoid interference with the larger exterior diameter portion of theguide tube 26 which extends forwardly from the exitway 50, and, tolocate locating recess 206 further to the right due to the increasedspacing between centres of the screws shown in FIG. 7.

FIGS. 8 and 9 are views identical to FIGS. 6 and 7 but showing a thirdembodiment of the invention in which the second engagement section 47includes a forward nose portion 300 in which the sidewall 234 extends360° about a screw. Rearward of forward nose portion 300, theentranceway 212 is provided for access of the washer 208. The forwardnose portion 300 is shown as having its interior surface taperinginwardly and forwardly to assist in camming the washer 208 into coaxialalignment on downward movement and to prevent a washer from being caughton the rearward edge of the forward nose portion 300. The guide tube 26of FIG. 9 may be used in a driver without footplate 200.

It is to be appreciated that the guide tube 26 for example as shown inFIGS. 4 and 5 is adapted to drive the screws 12 having a shape and sizeas shown in FIG. 5. To drive screws 12 having a different diameter orlength it is necessary merely to replace the guide tube 24 by adifferent guide tube 26. This can be done in the context of FIG. 5,merely by removing the cover plate and possibly the bit. In some cases,for example to switch from the configuration of FIG. 4 to that of FIG.6, the footplate 200 needs to be replaced or if provided to beadjustable, adjusted to move the recess 200 to a correct spacing. Pawl78 can be configured via its feed linkage to advance screw strips withdifferent spacings between screws. Changing of the guide tubes 26 can bewithout substantial disassembly. Guide tube 26 is preferably made ofwear resistant material and as it is removable this can assist inextending the life of the tool.

While preferred embodiments show tools having removable guide tubes 26,this is not necessary and a permanent guide tube 26 could be utilized.

In FIG. 7 the exitway 50 is shown to also provide forward surface 93 toassist in locating the strip 14.

Reference is now made to FIGS. 10 to 13 which show a fourth embodimentof the present invention in which the screw strip 14 is modified toprovide a locating system to permit location of the strip 14 relativethe guide tube 26.

FIG. 10, shows screws 12 held in a plastic holding strip 14substantially in accordance with Canadian Patent 1,054,982, thedisclosure of which is incorporated herein by reference. The stripcomprises an elongate thin band formed of a plurality of identicalsleeves 104 interconnected by lands 106. A screw 12 is received withineach sleeve 104. Each screw 12 has a head 16, a shank 108 carryingexternal threads 114 and a tip 116. As shown, the external threadsextend from below the head 16 to the tip 116.

Each screw is substantially symmetrical about a central longitudinalaxis 112. The head 16 has in its top surface a recess 13 for engagementby the screwdriver bit 24.

Each screw is received with its threaded shank 108 engaged within asleeve 104. In forming the sleeves about the screw, as in the manner forexample described in Canadian Patent 1,040,600, the exterior surfaces ofthe sleeves come to be formed with complementary threaded portions whichengage the external thread 114 of the screw 12. Each sleeve 104 has areduced portion between the lands 106 on the first side of the strip andtherefore on the first side of each screw. This reduced strength portionis shown as a substantially vertically extending longitudinal slot 118bridged by two thin strap-like portion or straps 120.

The strip 14 holds the screw 12 in parallel spaced relation a uniformdistance apart. The strip has a forward surface 122 and a rear surface123. Locating notches 124 are provided in the strip extending upwardlyfrom the forward surfaces 122 with the notches 124 spaced from eachother the same distance that the screws are spaced. Notches 124 arepreferably formed at the same time that the strip is formed by anextrusion process which, in effect, captures the screws between tworotating forming wheels. The forming wheels may be modified so as toform the plastic strip with the suitably spaced notches.

The notches 124 are formed with a notch leading ramp-like engagementsurface 142 and a notch trailing ramp-like engagement surface 144.

FIG. 11 shows an enlarged view of a guide tube 26 similar to the guidetube of FIG. 5 but with the exitway 50 having its forward surface 93provide a tooth-like projection 136 which is shaped to correspond to thenotches 124 in the strip.

As seen in FIG. 11, the forward surface comprises a projection leadingramp-like engagement surface 146 and a projection trailing ramp-likeengagement surface 148 which define the projection 136 therebetween.

A single cycle of driving one screw 12 and advancing the strip so as toposition the next screw is now described with reference to FIGS. 11, 12and 13.

FIG. 11 shows the screwdriver assembly at a point in time in a cyclewhen the screwdriver bit 24 has moved forwardly to engage the recess inthe screwdriver head and to initially urge the screw 12a towards theworkpiece. The forward surface 122 of the strip is urged into engagementwith the forward surface of the exitway 50 with the tooth-likeprojection 136 received in mating registry in the notch 124 of the screwstrip preceding the screw 12a to be driven. The screw 12a to be drivenis thus positioned by reason of its head 16 engaging the sidewall 34 ofthe guideway 32 and the strip having its notch 124 engaged with theprojection 136 of the exitway. Subsequently, the screwdriver shaft 20moves forwardly and drives the screw into a workpiece and, in so doing,the head of the screw passes through the sleeve 104 of the striprupturing the straps 120.

FIG. 12 shows a subsequent position in a cycle in which after fullydriving the screw, the bit 24 has been retracted and the screw feedmechanism is in the process of advancing the screw strip towards theleft. In the slide pawl 78 moving the next screw towards the left,disengagement of the projection 136 in the notch 124 is assisted byinteraction between the notch trailing surface 144 and the projectiontrailing surface 148 camming the strip rearwardly away from theprojection 136 of the forward surface. The screw feed mechanism advancesthe strip towards the left until the head 16 of the next screw 12engages the guideway inner surface 34 as shown in FIG. 13 with the notch124 in rough alignment rearward of projection 136.

From the position in FIG. 13, the cycle then returns to the positionshown in FIG. 11 with the bit 24 moving forwardly to engage the screwhead and urge both the screw and its strip forwardly. In the strip beingmoved forwardly from the position of FIG. 13 to the position of FIG. 11,the surfaces of the projection and notch interact to assist inengagement of the projection and notch. Engagement between trailingand/or leading surfaces of the projection and trailing and/or leadingsurfaces of the notch will cam the strip to move it to the left or theright to locate the notch precisely on the projection. Thus, theinteraction between the surfaces of the projection and tooth will movethe strip transverse to the axis of the guide tube 26, that is, alongthe longitudinal direction of the strip 14.

In the context of a power screwdriver as shown in FIGS. 1 to 3, the feedpawl 78 in each cycle on being moved to the right so as to be able toadvance the next screw to the right of the pawl 78, to some extentfrictionally engages the strip 14 and its screws 12 and can draw thestrip 14 back to the right. Such "feed pawl drawback" can bedisadvantageous. However with a notched screw strip of FIG. 10, theengagement of the notch 124 and the projection 136 can advantageouslyavoid the disadvantage of the strip being drawn back by feed pawldrawback beyond a desired position with the screw in alignment with thebit 24. To avoid feed pawl drawback the projection leading surface 146and the notch leading surface 142 may preferably be perpendicular to thelongitudinal along the strip and thus parallel the drive shaft axis.Feed pawl drawback may be intentionally designed to occur and beutilized as a vehicle for ensuring positive location of the notch 124 onthe projection 136.

In the preferred embodiments shown, the forward surface 93 of theexitway 50 is provided with projection 136 to engage notch 124 in thestrip. The provision of projection 136 and uniformly spaced notches 124are advantageous to form a system for locating the strip. The projection136 and notches 124 may have different configurations. For illustrationthe projection and notch have been shown to extend about 1/3 of thewidth of the strip. It is to be appreciated that smaller notches couldreadily be used. The notches and projections may have many other shapesthan that shown.

The preferred embodiment shows forward surface 93 having a projection136 which is generally uniform in a direction transverse to thelongitudinal of the strip. Surface 93 and/or its projection 136 could beprovided to vary in a direction transverse to the longitudinal to assistin locating the strip in a desired position in this direction. However,in the use of a screw strip, it is to be appreciated that latitude needsto be given for the strip to deflect transversely to the longitudinal ofthe strip in the head of the screw forcing itself through the sleeve andpast the strip.

The extent to which notches and projections may be desired in anyscrewdriver assembly will vary to some measure with factors which willinfluence the accuracy with which a screw comes to otherwise bepositioned in the guideway. The length of the screw; the nature of thescrew head such as whether it has a square recess or Phillips recess andwhether a screw head may be shaped for engagement by a socket; theextent to which the screw head is closely sized to the diameter of theguideway; the relative position of the strip on the screws compared tothe location of the head; and where, how and if the advancing pawlengages the screw and/or its strip; are all features which have abearing on whether projections and notches may be desired.

In addition to the forward surface 93 of the exitway, specific locationof the side surface 94 and rear surface 95 of the exitway may also beadvantageous. The side surface 94 may, to some measure, engage surfacesof the strip to assist in locating the strip within the exitway. Therear surface 95 must, in the embodiment of FIGS. 10 to 13 shown in whichthe strip must move rearwardly for the notches 124 to disengage theprojection 136, be provided sufficiently rearwardly from the forwardsurface 93 that the strip can move rearwardly and clear the projection136. In other configurations such as in FIGS. 1 to 9 in which theforward surface 93 does not incorporate a projection but merely extendsradially, the rear surface 95 may be provided spaced from the forwardsurface 93 a distance only marginally larger than the height of thestrip so as to assist in accurately guiding the strip therethrough.

In the context of screw strips utilizing notches to engage a projection,the screw feed mechanism could incorporate feed pawls which activate soas to assist in directing the screw strip rearwardly for disengagementof the pawl and for subsequent movement forwardly once the nextsubsequent notch comes to be aligned above the projection.

While the embodiment of FIG. 10 shows notches 124 in the strip 14 and amating projection 136 of the guide tube 26, it is to be appreciated thatprojections could be provided on the strip and notches about exitway 50of the guide tube. Similarly in replacement of any notches orprojections, shoulders, steps and the like could be substituted.

The invention has been described with reference to the particularconstruction of U.S. Pat. No. 4,146,871 for a power screwdriverincorporating the guideway received in a slide body. It is to beappreciated that the invention may readily be adapted to other knownfastener installation tool configurations including nut drivers and thelike and both power and manual tools.

The invention has been described with reference to a preferredscrewdriver assembly which incorporates an automatic screw feedassembly. The invention is, however, readily adapted for use with otherscrew feed assemblies and, as well, for unautomated, manual screw feedsystems. For example, in the context of FIGS. 1 to 6 the feed mechanismelements, namely lever arm 68 and/or pawl 78, could be eliminated. Thescrew strip could be advanced merely by a user manually grasping thestrip where it exits the exitway 50 and drawing the strip to the leftafter each screw has been driven. A simple tool would result havingincreased simplicity particularly suitable for manufacture at low priceand sale to the household.

FIG. 14 shows a pictorial view of the guide tube 26 shown incross-section in FIG. 10 and illustrating features in accordance with afifth embodiment.

As seen in FIG. 14 the guide tube 26 has many similarities to the guidetubes 26 in the other embodiments and is adapted to form a guide tubefor use, for example in substitution for the guide tube of FIGS. 5 and6. The entranceway 48 is shown closely sized to the shape of the screws12 and with an enlarged head entrance portion 414 and a reduced shankentranceway 416. This has the advantage that in a screw being drivenonce the head advances forwardly past enlarged head portion 414 thesidewall 34 extends about the head more than 180° so as to positivelylocate the head coaxially in the guideway. The guide body has at itsforward end a touchdown ring 416 which extends 360° about a screw beingdriven.

The exitway 50 is enclosed in the sense that it is bounded on both sidesas well as by its forward surface 93 and rear surface 95.

In the embodiment of FIG. 14, the rear surface 95 of the exitway 50 maypreferably be spaced a distance above the rearward most point ofprojection 136 equal to or marginally less than the width of the stripbetween forward surface 122 and rear surface 123. By having thisdistance less than the width of the strip, on the strip being moved tothe left, the land 106 will become compressed across its width and willdeflect to permit the strip to be moved to the left. This deflectionwill inherently bias the strip 14 towards the projection 136 such thatthe notch 124 cannot become disengaged from projection 136 withoutcompressing the width of the strip. Alternate embodiments to accomplishthis could provide a spring loaded mechanism carried by guide tube 26rearwardly of the strip 14 to bias the strip 14' where it exits theslide body 52 downwardly into the support surface 93. Such mechanismswould appear advantageous in a manual system in which a user manuallyadvances the screw strip to ensure that in handling the power toolbetween driving screws that the screw strip may not be dislodged orbecome improperly positioned. In a manual system, it may also bepreferable to have a one-way pawl not dissimilar to pawl 78 whichpermits a screw to advance to the left as seen in the FIG. 14 but doesnot permit the screws once advanced to move back to the right. Such apawl could act on any of the screws in the screw advance guideway 206.

With the invention of the present application, an advantage is thatinsofar as the strip is supported by portions of strip preceding a screwto be driven, the system of the present invention permits the last screwin any strip to be driven and is particularly advantageous for use withshorter length strips such as six to fifty screws in length. Thisadvantage arises whether or not a footplate 200 as illustrated in FIGS.1 to 6 is utilized in that even with a footplate 200 to pinch the nextscrew 12b to be driven, when a last screw 12a is being driven and thereis no screw 12b, support of the last 12a is more particularly desired.

The present invention provides a number of different mechanisms forlocating a screw 12a to be driven in alignment with the drive shaft 20.These include the engagement of a head 16 of a screw with the sidewall34 in first engagement portion 42 in the guide tube, the engagement of awasher 208 with the sidewall 234 in the second engagement portion 47 inthe guide tube, the engagement of the rearward surface 122 of a strip onthe forward surface 93 of the exitway, the engagement of indexingnotches 124 on the strip with complementary projections 136 in theforward surface 93 of the exitway, the engagement of the forward surface123 of a strip on the rear surface 95 of the exitway, and the holding ofa next screw 12b to be driven by the footplate 200. The use of any oneor more of these mechanisms may be sufficient to locate a strip withoutuse of other of the mechanisms. For example in the context of all theembodiments shown the footplate 200 is not required and the screw 12 canadequately be located for practical use merely by eliminating thefootplate or eliminating the portion of the footplate 200 carrying therecess 208 with or without affixing the remainder of the foot body tothe slide body against relative sliding motion. The embodiment of FIG. 9is particularly adapted for use with the engagement between the notch124 and projection 136 and the engagement between the screw head 16 andthe sidewall 34 to locate the screw. In the context of FIGS. 6 and 7,the footplate is not required due to second engagement portion 234. Ofcourse the embodiment of FIGS. 1 to 7 could be provided with stripshaving notches 124 to be engaged by projection 136.

Reference is now made to FIGS. 15 to 19 which show as a fifth embodimentof the present invention, another plastic holding strip 14 of the typetaught by Canadian Patent 1,054,982. The same reference numbers as usedto describe FIGS. 10 to 13 are used in FIGS. 15 to 19.

As is the case with the strip of FIGS. 10 to 13, the lands 106 in FIGS.15 to 19 are shown as extending both between adjacent screws 12, thatis, horizontally as seen in the rear view of FIG. 19, and axially of thescrews 12, that is, in the direction of the longitudinal axes 112 of thescrews. Thus, the lands comprise webs of plastic material provided overan area extending between sleeves 104 and between the forward surface122 and the rear surface 123. As best seen in FIG. 17, showing across-sectional end view through one land 106, the land 106 effectivelyis disposed about a plane indicated as 115 in FIG. 17 which is parallelto a plane in which the axes 112 of all the screws lies. Thus, the lands106 comprise a web which is disposed substantially vertically comparedto the vertically oriented screws as shown in the figures. The lands 106and the sleeves 104, in effect, are disposed as a continuous, verticallydisposed strip along the rear of the screws 12, that is, as a stripwhich is substantially disposed about a plane 115 which is parallel to aplane containing the axes of all screws.

As shown in dotted lines, the strip 14 of FIGS. 15 to 19 could beprovided with slots 124 in its forward surface 122, if desired. Thestrip 14 could also be provided with a horizontally extendingreinforcing flange 125 along its length as illustrated by the dottedlines in FIG. 18. The lands 106 are shown as spaced to one side of axes112 of the screws, however, this is not necessary, and the lands 106could be provided in alignment with the axes or otherwise. A preferredfeature of the strip is that it may bend to assume a coil-likeconfiguration due to flexibility of the lands 106, such that, forexample, as seen in a plan view to FIG. 15, the strip could be disposedwith the heads of the screws disposed into a helical coil, that is, theplane in which all the axes 112 of the screws lie may assume a coiled,helical configuration to closely pack the screws for use. Having thelands 106 and sleeves as a vertically extending web lying in the planeparallel that in which the axes 112 permits such coiling.

While the invention has been described with reference to preferredembodiments, the invention is not so limited. Many variations andmodifications will now occur to a person skilled in the art. Fordefinition of the invention, reference is made to the following claims.

I claim:
 1. In combination a holding strip and a plurality of threadedfasteners,the strip holding the fasteners spaced from one another in arow, the strip comprising spaced parallel sleeves interconnected bylands with one of the fasteners received in each sleeve, each fastenerhaving a head at one rear end, a tip at the other forward end and athreaded shank extending from below the head to the tip, each fastenerreceived in each sleeve spaced a uniform distance from adjacentfasteners with the fastener's head extending from one rear end of thesleeve and the fastener's tip extending from the other forward end ofthe sleeve, the sleeve threadably engaging the threaded shank, thesleeve having a reduced strength portion between the lands such that afastener on being threaded tip first into a workpiece is automaticallyseparated from its sleeve while simultaneously maintaining the length ofthe strip substantially intact and while guiding the fastener bythreaded engagement of the fastener in its respective sleeve, the landshaving a forwardly directed surface between the sleeves adapted tosupport the strip, the forwardly directed surface being spaced aconstant distance rearwardly from the tips of the fasteners.
 2. Acombination as claimed in claim 1 wherein the lands extend between thefasteners as a web which extends both between adjacent fasteners andaxially of the fasteners.
 3. A combination as claimed in claim 2 whereinsaid web is disposed substantially about a plane parallel a planecontaining axes of all fasteners.
 4. A combination as claimed in claim 2wherein the sleeves extend along a portion of the threaded shank in anaxial direction thereof and comprise inwardly facing threads forreceiving the threaded shank.
 5. A combination as claimed in claim 4wherein the sleeves only partially surround said fasteners to form saidreduced strength portion.
 6. A combination as claimed in claim 2 whereinthe sleeves completely surround the threaded shank of each fastener andare formed with longitudinal aligned perforations along one sidethereof, substantially between the lands, defining said reduced strengthportion, the perforations are formed by strap-like wall portions of eachsleeve.
 7. A combination as claimed in claim 1 wherein the lands extendbetween the fasteners as a web which extends both between adjacentfasteners and axially relative the fasteners,each fastener having anaxis extending axially therethrough, the web being disposedsubstantially about a plane containing the axis of every screw.
 8. Acombination as claimed in claim 7 wherein the web being sufficientlyresilient to permit the screw strip to be coiled with the planecontaining the axis of every screw disposed in a helical shape.
 9. Acombination as claimed in claim 7 whereinthe strip holds the fastenerswith the axes of the fasteners parallel each other, and the forwardlydirected surface disposed normal the axes of the fasteners.
 10. Acombination as claimed in claim 9 wherein the threaded fasteners aresubstantially of identical size.
 11. A combination as claimed in claim10 wherein the threaded fasteners comprise fasteners.
 12. A combinationas claimed in claim 11 wherein the strip comprises plastic.
 13. Acombination as claimed in claim 1 wherein the strip comprises plastic.14. A combination as claimed in claim 9 further comprising locatingnotches provided in the forwardly directed surface between adjacentfasteners spaced a distance from adjacent notches equal to the uniformdistance the fasteners are spaced.